This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Brain tumors in rats will be imaged by MI through the scalp and scull, through the scull, and after craniectomy. This is done to study the potential of MI to image tumors covered by normal tissue layers. Tumors will also be imaged after photodynamic therapy. This is done to study the potential of MI to monitor treatment response by functional imaging of blood content and oxygenation. The brain tumor bearing rats are part of an ongoing study at the BLI.